1. Field of the Invention
This invention relates generally to plastic screw grommets and more particularly, it relates to an improved sliding grommet of the type to be inserted and retained freely floating in a fitting hole in a mounting panel and thereafter to receive a threaded element, such as a screw, for mounting a mating panel having a throughhole to the mounting panel. The sliding grommet is adapted to absorb variations in the relative positions of the fitting hole in the mounting panel and the throughhole in the mating panel caused by thermal expansion and contraction due to temperature changes.
2. Description of the Prior Art
A state-of-the-art search directed to the subject matter of this application uncovered the following patents:
Klump, Jr. U.S. Pat. No. 2,424,757; Takagawa et al U.S. Pat. No. 4,358,234; Kraus U.S. Pat. No. 4,787,795; Okada U.S. Pat. No. 4,865,505; and Sato U.S. Pat. No. 4,927,306.
British Pat. No. 1,139,976.
There is disclosed in U.S. Pat. No. 2,424,757 a self-locking integral bushing which includes a body portion 1 terminating at one end in a circular flange 2 and upwardly extending fingers 3 located between the flange and the opposite end of the body portion. The fingers are provided with a plurality of shoulders 7, 8 and 9 to accommodate the bushing to plates of different thicknesses. As the bushing is pushed through a hole in the plate, the fingers will be forced inwardly until they pass the outer surface of the plate and then snap back so that one of the shoulders will engage the plate and lock the bushing in place.
There is disclosed in U.S. Pat. No. 4,358,234 a part fixing system for fixing the part to the object by the combined use of at least one retaining clip 15 for determining the position of the part relative to the object and a plurality of retaining clips 14 for absorbing possible positional deviation between the stud bolts of the part and the corresponding holes in the object. Each of the retaining clips 14 includes a nut member 17 adapted to be screwed to the bolt and a plurality of deformable engaging pieces 18 extending divergingly from one end of the nut member, and grooves 19 cut in the leading edges of the engaging pieces for resilient engagement with the edges of a fixing hole in the object.
There is taught in U.S. Pat. No. 4,787,795 a push-in fastener which includes an elongated body 3, an enlarged head 5 joined to the upper end of the body and a pair of resilient arms 1 and 2 joined integrally to the body. The arms are located diametrically opposite one another and extend at an angle toward the head. The free end zones of the arms have catch openings or notches 15, 16 which engage the underside of a workpiece opening when the fastener is inserted therein. The body 3 includes cylindrical guide sections 6, 7 which lie opposite each other and are displaced 90.degree. radially from the arms. Upper and lower truncated cone sections 9 and 8 are formed above and below the cylindrical sections.
U.S. Pat. No. 4,865,505 shows a part mounting structure which includes a U-shaped metal leaf spring member 2 for receiving a boss portion 1a of a part 1, and a clip member 3 for receiving the leaf spring member and for engaging a mounting oblong hole 5 of a panel 4. The clip member is formed of a flange 8 and two pairs of engaging portions 10 projecting outwardly from the opposite outer walls 3a on its long side thereof. A pair of elastic engaging legs 13 are formed on the opposite outer walls 3b on the short side of the clip member and project upwardly therefrom. The clip member is easily moved and centered within the oblong hole since the engaging portions 10 and the engaging legs 13 are engaged with the edge of the oblong hole.
U.S. Pat. No. 4,927,306 shows a screw grommet 1 formed of an enlarged head part for abutting against the surface of a mounting panel 11 and a shank 3 for engaging an oblong fitting hole 12 bored in the mounting panel. The shank includes a pair of elastic arms 6 disposed on the opposed walls 3b and extending therefrom at a prescribed angle. Each arm has a stepped underend 6a for elastic engagement with the edge of the fitting hole. If a part 13 to be mounted expands or contracts to induce a variation in the relative positions of the fitting hole 12 bored in the mounting panel and throughhole 14 bored in the part, the screw grommet is capable of absorbing the variations in the hole positions since the shank 3 is allowed to easily slide inside the oblong fitting hole due to the bending in the elastic arms 6 into the empty spaces 7.
Finally, British Pat. No. 1,139,976 describes a two-part fastener comprising a support engaging part A and a retaining pin B. The engaging part A has a body 1 formed with a flange 2 at its one end and resilient wing-like elements 3, 4 disposed on its two opposite sides. The wing-line elements are flexible inwardly to enable the body to be snapped through an apertured support B. An apertured member to be secured is positioned over the support so that its aperture is aligned with the aperture in the support. The retaining pin is inserted axially through these apertures and into the bore in the body 1.
However, none of the prior art uncovered in the search disclosed a sliding grommet having a head flange and a shank portion of a unique construction like that of the present invention which is capable of absorbing relative positions of an oblong fitting hole in a mounting panel and a throughhole in a mating panel to be attached caused by thermal expansion and contraction. This is accomplished by a pair of Y-shaped resilient members disposed on opposite sides of the shank portion to permit flexing upon insertion and by providing locking tabs on each leg of the Y-shaped members for retaining freely floating the shank portion in the oblong fitting hole in the mounting panel so as to permit lateral sliding engagement between the upper and lower edges of the fitting hole. As a result, the grommet after fixation in a mounting panel allows for thermal expansion and contraction of the mating panel due to changes in the ambient temperatures causing variations in the relative lateral positions of the fitting hole and the through-hole.